Safety razors of the type having a pair of tandemly mounted blades permanently mounted in a disposable cartridge are becoming increasingly popular. In such cartridges the blades are separated by a spacer, and the cutting edge of the upper blade is spaced slightly rearwardly of the cutting edge of the lower blade. A construction of such razor blade assemblies which is currently commercially popular is disclosed in the patent to Dorion, Jr., U.S. Pat. No. 3,724,070. Other disposable dual blade cartridges of the general type disclosed in the Dorion patent also are known, but the general construction and arrangements are similar to that disclosed in the Dorion patent. Such constructions, for example, are shown in the Perry patent, U.S. Pat. No. 3,768,162, and the Dorion et al patent, U.S. Pat. No. 3,786,563.
A problem which exists with dual blade disposable cartridges of the type disclosed in the above-mentioned patents is that the space between the tandemly mounted blades quickly becomes filled with hair and shaving residue since there is no provision for passing this residue from between the blades. The spacer blocks such passage. The spacer, however, is necessary because the blades are extremely thin and are not capable of maintaining the uniform space between them without the aid of a spacer. To overcome the problem of the accumulation of shaving residue, mechanical cleaning devices or movable spacers have been proposed. One such proposal is shown in the patent to Chao, et al, U.S. Pat. No. 3,972,114, which employs a reciprocating toothed spacer between the blades; so that the user may impart manual reciprocatory motion to the spacer as the cartridge is washed. A similar approach, using a mechanical movable spacer, is commercially available where the spacer is spring biased to a position just rearwardly of the cutting edge of the upper blade and may be manually moved forwardly against the bias of the spring to push the residue to a position generally overlying the cutting edge of the lower blade. In this position, the residue then may be washed away by the user. Such a device is disclosed in the patent to Ishida, U.S. Pat. No. 4,047,296. Both of these mechanical structures, however, require moving parts bvetween the blades; so that a tight bonded engagement of the blades with the spacer is not possible in the cartridge construction. Furthermore, it is necessary for the user to engage the cartridge and manually manipulate the spacer in some way or another during the rinsing action in order to remove the residue.
A relatively open dual blade construction for a safety razor is disclosed in the patent to Welsh, U.S. Pat. No. 3,660,893. The blades in this razor, however, are secured by the ends only and are placed under tension longitudinally of the cutting edges of the blades. When very thin blades are employed, which is the ideal condition for optimum shaving results, maintenance of the desired spacing between the two blades using the construction of this patent is difficult. A more rigid cartridge construction is desirable.
Another approach to providing some means for removing the residue from between the blades of a dual blade razor cartridge is shown in the Dawidowicz, et al patent, U.S. Pat. No. 3,783,510. The system shown in this patent has a spacer which includes channels in it to provide flow paths for shaving residue from between the cutting edges of the tandemly mounted blades. At the rear of the cartridge, a number of slots are provided; so that the residue can flow through the space and out the slots. A problem which exists in the structure of the Dawidowicz cartridge, however, is that the exit slots at the rear of the cartridge which communicate with the channels in the spacer necessarily are restricted in size. Consequently, the Dawidowicz cartridge, while it theoretically should be capable of cleaning out the residue from between the blades, as a practical matter still results in a construction where such cleaning is difficult to accomplish effectively.
Prior art solutions for cleaning single blade razors with replaceable blades in which the head is loosened for the cleaning operation are not applicable to disposable multiple-head cartridges in which the blades are not loosened or replaced.
Accordingly, it is desirable to provide a disposable razor blade cartridge unit employing tandemly mounted dual blades in which a provision is incorporated for readily and easily cleaning out the residue between the blades which accumulates during the use of the razor, without requiring partial disassembly of the cartridge, without requiring movable mechanical parts, and which overcomes the disadvantages of the various prior art devices discussed above.